A typical float valve can permit cement to be flowed out of a casing string and into an annulus formed between the casing string and a wellbore. The float valve prevents the cement from flowing back into the casing string. While the casing string is being installed in the wellbore, some float valves have an auto-fill feature that allows fluid in the wellbore to flow through the valve into the casing string, so that the casing string does not have to be filled from surface as it is installed.
Thus, it will be readily appreciated that improvements are continually needed in the art of constructing and operating float valves. Such improved float valves may be used in cementing and other operations in wells.